1. Technical Field
The present invention relates to a display substrate, and more particularly, to a method of forming a metal line and a method of manufacturing a display substrate by using the method of formings a metal line.
2. Discussion of the Related Art
Generally, a liquid crystal display (LCD) device includes a display substrate and a counter substrate coupled to the display substrate to receive a liquid crystal layer. The display substrate has gate lines, source lines crossing the gate lines, switching elements connected to the gate and source lines, and pixel electrodes connected to the switching elements. Each switching element includes a gate electrode extending from the gate lines, a channel insulated from and overlapped with the gate electrode, a source electrode formed from the source lines and electrically connected to the channel, and a drain electrode spaced apart from the source electrode and electrically connected to the channel.
Masks are employed in manufacturing the display substrate. In order to reduce manufacturing time and cost, the number of the masks needed to manufacture the display substrate is minimized. For example, a five-mask process employs one mask during each of a gate metal patterning process, a channel patterning process, a source metal patterning process, a contact portion patterning process, and a pixel electrode patterning process, and thus a total of five masks may be employed. A four-mask process may be similar to the five-mask process described above however a single mask is used during both the channel patterning process and the source metal patterning process, and thus a total of four masks may be employed.
In display substrates manufactured by the four-mask process, a source metal pattern and a channel pattern are patterned by using one mask. Therefore, the channel pattern is formed more protrusive than the source metal pattern. Having a more protrusive channel pattern reduces an aperture ratio and changes a coupling capacitance between the channel pattern and the pixel electrode. This may be due to a light leaked current, thereby changing waterfall effect noise and driving characteristics of the switching element to incur some problems such as an afterimage.